Exporting tiled texture?
So you are trying to make a tileset in unity3D, using blender?
I did just that. Mine is simple, like this:



Notice how the larger tile (to L-turn) is much larger than the others. Still, it is only one square texture for each of them. The trick is to UV-map it correctly.

Here is the UV-map for the L-turn. It wraps the texture twice.



Here is the UV-map for a simple tile. It wraps the texture once.

 

So for a long floor tile, you have two options. 


Make a square floor tile with simple UV-map in blender and repeat it several times in unity (preferred).
Make a long tile with "long" uv-map in blender and use it once in unity.


No baking!

If you bake a tiling texture to a polygon UV-mapped as yours you are ruining your texture resolution. If your texture (512px) tiles four times it has an effective resolution of 2048px (4x512). If you bake that to 512 you have reduced your texture resolution 4 times. You could bake it to 2048 and keep the resolution but you would end up with very large textures. 

It might also be so that unity downsamples your texture when building the game and you loos quality again. It is a matter of settings, target device and quality.

In any case, I advice against baking.

The reason that it works inside blender is that blender can use texture of odd resolutions and multiple textures per face.

You might be able to make a shader that combines two textures with different tiling in unity. But then how would you position it?